Anchor bolts have traditionally been installed in poured concrete floors by rigidly attaching the bolts to concrete forms, typically made of wood, and pouring the concrete floor such that the poured concrete sets around the bolt to embed the anchor bolt and hold it permanently in place. The imbedded anchor bolts can then be used to anchor fixtures, such as stadium seats, which are typically provided with predrilled bolt holes. A problem occurs when the bolts are positioned slightly askew or slightly offset in position, or when the predrilled bolt holes in the fixture vary somewhat in position from a predetermined bolt pattern. In these situations, if the anchor bolts are firmly imbedded in the concrete, an installer has little choice but to enlarge the bolt holes or over stress the bolts in an effort to conform them to the hole pattern, which often results in weakening the anchoring plate, breaking or otherwise damaging the anchor bolt, the concrete floor, etc.
A number of prior attempts have been made to construct anchor bolt retainers which allow some flexibility of the bolt position after pouring of the concrete. One example is found in U.S. Pat. No. 4,408,940 to Mark Fischer, entitled ANCHOR BOLT ASSEMBLY. This patent is directed to an anchor bolt anchor sleeve for poured concrete floors which includes a plate with a central bore through which an anchor bolt is preinserted and, optionally, tightened down to the plate via an internal nut. Concrete is poured around the sleeve, leaving a void in the hollow sleeve. The combination of the sleeve and the plate is said to allow some flexibility in bolt movement after the concrete is poured, apparently since the bolt can be more easily bent due to the void.
Another attempt to create a flexible bolt anchoring system is taught in U.S. Pat. No. 5,404,689 to Dennis DiNarda, and entitled ANCHOR BOLT SLEEVE. This patent is directed to an anchor bolt sleeve which surrounds an anchor bolt shank to prevent concrete from directly surrounding the shank. The sleeve is shown as being corrugated, allowing it to expand lengthwise to accommodate different bolt sizes. As in the Fischer patent, concrete is poured around the sleeve, imbedding the sleeve but leaving a void around the bolt. Again, the stated purpose is to allow the bolts to be bent in the void so that their position can be adjusted slightly to match varying bolt hole positions in fixtures to be installed.
In both the Fischer and DiNarda patents, the anchor bolts must still be bent to adjust the bolt position above the concrete. Bending an anchor bolt can be difficult and also inevitably weakens the bolt itself. Applying enough pressure to the bolt to bend it usually requires some type of leveraged tool, which can damage the threads of the bolt. Finally, concrete can be inadvertently poured directly into the open top of the Fischer sleeve, thus filling the intended void. The expandable sleeve body of the DiNarda patent cannot be readily attached to concrete forms and appears to be subject to failure due to the flexible sidewalls.
It is clear, then, that a need exists for a more convenient and effective construction bolt anchor and retainer which allows the bolt to be adjusted slightly in position after a concrete floor has been poured around it. Such an anchor bolt and retainer should allow adjustment of the bolt without bending or otherwise weakening or damaging the bolt itself.